Please explain the mechanism of acid catalysed dehydration of butan - 1-ol??

Dear Student,
The alcohol can be heated with mod. conc. sulphuric acid or conc. phosphoric(V) acid to produce an alkene. It is effectively an E1 elimination reaction since step (2) is the rate determining step.

R2CH-C(OH)R2 ==> R2C=CR2 + H2O

Alcohol                         ALKENE

General Mechanism: Acid - Catalysed Dehydration of an Alcohol

Step 1: Protonation of hydroxyl group

Step 2:  Ionization to carbocation

Deprotonation to give the alkene

The detailed mechanism of butn - 1- ol is shown below.
1.) The first step shows formation of carbocation.
2.) The second step shows formation of better carbocation by rearrangement by 1,2 hydride shift.
3.) Deprotonation to form alkene.


Regards